(1) Field of the Invention
The present invention relates generally to dispersing and grinding apparatus having a rotationally driven agitator for dispersing, grinding, and agitating a material by means of a grinding medium and more particularly, to a removable mounting structure for rotatably mounting the agitator and which can be removed from the apparatus without requiring removal of the agitator.
(2) Background Information
Dispersing and grinding apparatus are in widespread use for dispersing, grinding and agitating various types of materials. These apparatus are commonly known as dispersion agitators or grinding mills and employ a rotationally driven agitator in conjunction with a grinding medium, such as balls, beads or other particulates, to accomplish the grinding and comminuting action. After the material is suitably dispersed, ground and agitated, the processed material must be separated from the grinding medium. For this purpose, a separator is frequently installed at the discharge end of the apparatus for separating the processed material from the grinding medium such that the processed material is discharged from the apparatus whereas the grinding medium is retained in the apparatus for re-use.
One common type of separator is the so-called dynamic separator which comprises a stationary stator and a rotatable rotor. The stator and rotor are spaced apart a slight distance so that a small gap exists between the rim of the rotor and the stator to define a discharge passage for the processed material. The size of the gap is smaller than the size of the particulates which constitute the grinding medium thereby ensuring that the grinding medium cannot pass through the gap.
This type of dispersing and grinding apparatus typically employs a grinding vessel in which are charged the material to be processed and the grinding medium, and a rotary shaft extends into the vessel for rotationally driving the agitator. The rotary shaft is usually directly supported on the apparatus by rotary bearings, and sealing means, such as mechanical seals, packings and the like, are installed directly on the rotary shaft. Over prolonged periods of use, the bearings and seals become worn and require replacement. In the prior art constructions, the servicing and replacement of such parts are time-consuming and troublesome tasks because the bearings and seals act directly on the rotary shaft. As a consequence, it is necessary to extract the rotary shaft together with the agitator from the grinding vessel in order to service and replace the bearings and seals.
When the dispersing and grinding apparatus is equipped with a dynamic separator, the rotor, stator, and usually both, become quickly abraded by the abrading action of the grinding medium and, therefore, need frequent replacement. This is due to the fact that as the rotor rotates, the grinding medium tends to accumulate and concentrate at the rim area of the rotor. Consequently, the grinding medium is carried along with the rotating rotor and abrades and wears out the confronting surfaces of the stator and rotor. As the rotor is usually secured directly to the rotary shaft which rotationally drives the agitator, it is necessary to remove the rotary shaft from the apparatus in order to service or replace the worn rotor and stator. Moreover, in those constructions in which the agitator is secured directly to the rotary shaft, it is usually necessary to extract the agitator from the grinding vessel in order to remove the rotary shaft to enable servicing, repair or replacement of the worn parts of the separator. Such a procedure is time-consuming, troublesome and uneconomical.